Maximum value determining device



NOV. 17, 1959 wr, BlLz 2,913,174

MAXIMUM VALUE DETERMINING DEVICE Filed MaIOh 12, 1957 l YVIOO b SLT; A

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United States Patent O MAXIMUM VALUE DETERMINING DEVICE Wilhelm Biiz, Schwaig-Nuremberg, Germany, assignor t Siemens-Schuckertwerke Aktiengesellschaft, Erlangen, Germany, a corporation of Germany Application March '12, 1957, Serial No. 645,617 Claims priority, application Germany March 17, '195.6 9 Claims. (Cl. 23S-145) This invention relates to a device for determining the maximum number value of a series of numbers and has particular relation to such a device including relays energizable in response to actuation of a plurality of sets of keys corresponding to dilerent digit places of a number.

According to the invention a device of improved construction is provided for determining the maximum number value of a series of numbers. The device includes keying means comprising a number of control relays which are energizable in response to actuation of a plurality of sets of keys. The sets of keys correspond to different digit places of a number. For example, one set of keys may correspond to the hundreds digit of a number. Another set of keys may correspond to the tens digit of a number and a final set of keys may correspond to the units digit of a number. The keys of each set may represent different digits between zero and nine.

The control relays are arranged for energization from a suitable voltage source in response to actuation of the keys to eiect a number of control functions. Voltage from the voltage source is applied to the control relays by a voltage applicator which is effective to successively place the control relays under voltage in the digit place sequence starting at the highest digit place. The arrangement is such that the voltage applicator is elective to place the control relays under voltage in the proper sequence only if a digit ready for keying in the set corresponding to the highest digit place is equal to or larger than a digit previously keyed into such set.

The control functions exerted by the control relays include the establishment of a holding circuit for an energized control relay when a digit to be keyed into a set is equal to or greater than a digit previously keyed into such set. Such a holding circuit maintains energization of the control relay to effect the keying of a digit. The control relays are also effective when energized to prevent the subsequent keying of a digit in a set which is smaller than a digit previously keyed into such set.

Suitable erasing means is provided for erasing digits of a previously keyed number when a digit to be keyed into the set corresponding to the highest digit place is larger than the previously keyed digit. For this purpose erasing relays are provided for energization in response to the keying of a digit in a digit set which is larger than a digit previously keyed into such set. When so energized, the erasing relays effect interruption of the holding circuit of an energized control relay in the next lower digit set to thereby deenergize the control relay to permit the subsequent keying of digits in such lower set.

Suitable registering means is provided to eiect the registering or recording of a number in response to keying of the number. Preferably, such registering means is connected for operation through the voltage applicator when voltage is applied to the units digit set.

It is, therefore, an object of the invention to provide y 2,913,174 Patented Nov. 17, 1959 a device of improved construction for determining the maximum number value of a series of numbers.

It isanother object to provide a device as defined in the preceding paragraph including a number of relays energizable in response to actuation of a plurality of sets of keys corresponding to diterent digit places of a number with the keys of each set representing a different digit.

It is still another object of the invention to provide a device as defined in the preceding paragraphs including control relays effective when energized to prevent the elective keying of a digit in a set which is smaller than a digit previously keyed into such set.

It is a still further object of the invention to provide a device for determining the maximum number value of a series of numbers including control relays effective when energized to key digits of a number in key sets corresponding to different digit places of the number with erasing means elective in response to the keying of a digit in the set corresponding to the highest digit place which is larger than the digit previously keyed in such set for deenergizing control relays in the lower digit place sets.

Other objects of the invention will become apparent from the following description taken in conjunction with the accompanying drawing in which the single figure illustrates a maximum value determining device constructed in accordance with the teachings of the present invention.

Referring to the drawing, the single figure illustrates a device for determining the maximum number value of a series of numbers. The device illustrated is capable of investigating numbers having a maximum value of 999. It is to be understood, however, that devices may be constructed according to the invention which are capable of investigating a number having other maximum values such as 9,999.

The device illustrated includes voltage applicator means shown as enclosed in the broken line rectangle 12 for applying voltage to keying means illustrated as enclosed in the broken line rectangle 14. The voltage applicator 12 includes a manually actuable starting switch S1 which is effective when in a closed condition Ito prepare a iirst applicator relay having an operating winding A for energization in response to actuation of a hundreds key from a source of voltage which is represented by a battery 16. The winding A is eective when energized to operate a pair of normally open switches a1 and a2 to closed positions.

Closing of the switch a2 serves to prepare a second applicator relay including an operating winding B for energization in response to actuation of a tens key from the source 16 through the closed switches S1 and a2. Closure of the switch a2. also permits the application of voltage from the source 16 to control relays of the tens digit set of the keying means 14 in response to actuation of a tens key as will presently appear.

Energization of the winding B effects operation of a pair of normally open switches b1 and b2 to closed positions to thereby prepare a winding C of a third applicator relay for energization in response to actuation of a units key from the source 16 through the closed switches S1, a2. and b2. Closure of the switch b2 also permits the application of voltage from the source 16 to control relays of the units digit set of the keying means 14 in response to actuation of a units key. Energization of the winding C is elective to operate a pair of normally open switches c1 and c2 to closed positions. When the switch c2 is closed, an operating winding D of a registering relay is energized to operate a suitable registering device (not shown) for the.

purpose of registering or marking the value of a number keyed into the keying means 14.

1t will be recalled that energization of the windings A, B, C effects operation respectively of normally open switches a1, b1 and c1 to closedV positions. Closure of these switches operates to connect the associated applicator` relay windings for energization from the' source lr6-through the closed switch S1 and a conductorv M. This arrangementl operates to maintain energization of the applicator relay windings A, B and C when the actuable keys of the keying device 14 are released subsequent to actuation thereof. Suitable resistors VA, VB and VC are connected in series respectivelyl withy windings A, B and C to limit current ow through the associated windings.

The keying means 14 includes a plurality of sets of actuable keysV which represent4 respectively the hundreds digit, the tens digit and the units digit of a number. The keys of each set represent different digits between zero and nine. ln the single figure the keys of the hundreds set are represented by the reference characters T000, T100, T200, T300, T400, T500, T600, T700, T800 and T900. The keys of the tens set are represented respectively by the reference characters T00, T10, T20, T30, T40, T50, T60, T70, T80 and T90. ln a similar manner the keys of the units set are represented respectively by the reference characters T0, T1, TZ, T3, T4, T5, T6, T7, TS and T9.

A suitable control relay is associated with each of the actuable keys. For example, a control relay having an operating winding 100 is associated with the key T100 in the hundreds set. Each of these control relays includes a plurality of switches operable in response to energization of its operating winding to eiect a number of control functions. As an example', energization of the winding 100 of the control relay for-the key T100 in the hundreds set is effective to operate tive switches 100-1, 100-2, 100-3, 100-4 and 100-5. The eiect of these switches will be described hereinafter. The control relays for the tens and units sets are similar except that the control relays for the units set excepting the zero digit relay include but two switch instead of live switches as is the case for the control relays of the hundreds and tens sets with the exception of the zero and nine digits in these sets.

Each applicator relay winding is included in a separate conductor through which it is initially energized in response to actuation of a key in the associated key set. For example, the winding A of the tirst applicator relay of the voltage applicator 12 is connected in a conductor H100 to which is connected a key contact of each key inthe hundreds set. lnv a similar manner windings B and C of the following applicator relays are included in conductors H and H1. Key-contacts of keys in the tens and units set are connected to these conductors.

A separate self-holding conductor forV the control relay windings of each key set is connected to the positive terminal of the source 16 through a conductor N1. For example, the conductor G100 forms part of a holding circuit for the windings of the control relays or" the hundreds set. In a similar manner self-holding conductors G10 and G1 are provided for the control relay windings in the tens and units sets. The conductors G100, G10 and G1 comprise portions of paths through which energization of the respective control relay windings is maintained subsequent to the release of an actuated key.

As will presently appear, energization of an operating winding is effected subsequent to energization of an associated erasing relay through conductors K100 and K10 included respectively in the hundreds and tens sets. The control relay windings are connected to these conductors d in response to energization of the erasing relay windings through conductors 1100 and 110.

Each of the control relays includes switches which are effective when operated in response to energization of the associated operating winding to change the path of energization of the associated operating winding. For example, the control relay for the key T100 includes a normally open self-holding switch 100-1 having a terminal connected to the conductor G100. Closure of the switch 100-1V is effective to connect the winding 100 to the conductor G100 for maintaining energization of the winding 100 subsequent to release of the actuated key T100. Similar self-holding switches are provided for the control relays in the tens and units sets.

The control relays forV the hundreds and tens sets each includes a normally open switch for connecting the operating windings to the conductors R100 and K10. For example, the relay for the key T100 includes a switch 100-2 having one terminal connected to the conductor J 100 through which the winding 100 is initially energized and having a second terminal connected to conductor K100'through which the winding 100 is energized subsequent to closure of the switch E100-2. A similar switch is included in each of `the control relays for the tens set. However, such a switch is not employed in the control relays for the units set.

Each of the control relays for the hundredsv and tens set also includes a normally closed switch forrinterrupting the conductor through which the associated operating winding is initially energized. This switch for the control relay of the key T100 is represented by the reference numeral 100-3 and is included in the conductor 1100. The control relays for the tens set include similar switches represented by the numerals 10-3, 20-3, 30-3, etc. which are included in the conductor 110 forming a part of the circuit through which the associated operating windings are initially energized.

Each of the control relays for the hundreds and tens sets with the exception of the relays for the zero keys in such sets includes a pair of normally closed switchesl operable to open positions when the associated operating winding is energized to prevent subsequent keying of a digit in a set which is smaller than a` digit previously keyed in such set. For example, the controlY relay for the key T100 includes switches 100-4 and100J-5 connected respectively in the conductors 1100 and K100. When the winding 100 is energized, the switches 100-4 and 100-5 are opened to interrupt theY paths which include the conductors 1100 and K100 to thereby prevent energization of the windingr000 in responseto actuation of the key T000. The control relays in the units set each 4 includes a single switch for this purpose. These switches are represented by the reference characters 1&2, 2 2, etc. and are included in the conductor K1.

ln order to erase a digit previously keyed into a digit Y set when a digit to bev subsequently keyed in. such set is equal to or larger than the previously keyed digit, suitable erasing means is provided. As illustrated in the single igure, the erasing means is enclosed in the broken line rectangle 10. Such erasing means includesV a pair of relays connected for energization in response to actuation of keys in the hundreds and tens sets. These erasing relays include respectively operating windings E and F each effectivewhen energized to `operate a plurality of switches.

For example, the winding E operates when energized a plurality of switches e1, e2, e3 and e4. In a similar manner, the winding F operates switches. f1, f2, f3 and f4. The normally open switches e1 and ff are elective when operatedY to closed positions to establish holding circuits for the associated windings E and F to maintain energization of these windings through conductors H and H10 when actuated keys in the hundreds and tens sets are released.

The normally closed switches e2 and f2 of the erasing relays are included respectively in the conductors J 100 and J to interrupt these conductors when operated to opened positions. The erasing relays also include normally open switches e3 and f3 effective when operated to connect the control relay windings for the hundreds and tens sets to conductors K100 and K10 respectively. The switches e2, e3 and f2, f3 cooperate to remove the windings E and F from the paths Aof energization of the control relay windings to increase current through the control relay windings. This increased current is sufficient to effectively energize the control relay windings.

The erasing relays include finally switches e4 and f4 which effect the erasing function. For this purpose, the switches e4 and f4 are included in a conductor Q which forms a portion of the holding circuits for the operating windings of the control relays in the tens and units sets. These switches are effective when operated in response to energization of the windings E and F to interrupt the conductor Q to thereby deenergize control relays of the tens and units sets for effecting the erasing function. A pair of manually operable switches S2 and S3 are in cluded in the energizing circuits for the windings E and F to effect `deenergization of these windings for permitting subsequent keying of digits in the tens and units sets. It is noted that no erasing relay is provided for the units set.

The applicator, control and erasing relays are designed so that the switches of these relays in a given digit set operate in a preselected sequence in response to actuation of a key in such set. The arrangement is such that applicator relay switches are the first to operate followed by erasing relay switches and finally control relay switches.

Operation of the device will now be described. All of the relay switches and manually operated switches are initially in the positions illustrated in the single fig ure. Let it be assumed that it is desired to key the number 444 into the device.

The switch S1 is initially closed and the key T400 is actuated to bridge its associated key contacts. When this key is actuated, current will flow `from the positive terminal of the source 16 through the closed switch S1, the winding A, the key T400, the winding 400, the switch 400-3, conductor 1100, switch e2, winding E, the switch S2 and back to the negative terminal of the source 16 through a switch S4. Such current flow is effective to initially energize the winding A to operate the associated switches to positions other than those shown in the single figure. Switch a1 is closed Vto maintain energization of the winding A through the conductor M and the switch S1. Switch a2 is also'closed to prepare the winding B for energization in response to actuation of a key in the tens set.

Prior to operation of the control relay switches the winding E is energized to operate its switches. The switch a1 is thereby operated to a closed position to establish a holding circuit for the winding E to maintain energization of this winding through the conductor H100 independently of the conductor J 100. At the same time switch e2 is opened to disconnect the winding E from the conductor 1100. Closing of the switch e3 is effective to connect the winding 400 to the conductor K100 through the conductor 1100. The erasing switch e4 is opened to interrupt the conductor Q but without any elfect at this stage. Since winding E is now removed from the path of energization of winding 400, current through winding 400 is now suicient to cause operation of switches associated with winding 400.

y Energization of the winding 400 operates to close the switch 400-1 to maintain energization of the windin-g 400 when the key T400 is released through a portion of the conductor G100. At the same time, switch 400-2 is `closed to connect the winding 400 to the conductor K100.

At the same time switch 400-3 is opened to interrupt that portion of conductor 1100 which is associated with the digits of the hundreds set larger than the digit 4. The switches 400-4 and 400-5 are also at this time opened to interrupt respectively portions of the conductors 1100 and K which are associated with control relay windings for digits smaller than the digit 4 in the hundreds set.

It is observed now that energization of the winding 400 is maintained `from the source 16 through the conductor N1, conductor G100, switch 400-1, switch 400-2 and that part of conductor K100 which extends beneath switch 400-5. It is also noted that energization of the winding E is maintained through the conductor H100 independently of the winding 400 to thereby permit sufficient current fiow through the winding 400 to maintain its energization. At this stage the digit 4 is effectively keyed into the hundreds set. The next action involves the manual opening of the switch S2 for the purpose of deenergizing the winding E. This results in a return of the switches associated wth the winding E to the positions shown in the single figure.

In order to key the digit 4 of the number 444 into the tens set, the key T40 is actuated to bridge the associated key contacts. This results in currentflow from the positive terminal of the source 16 through closed switches S1 and a2, winding B, conductor H10, key T40, winding 40, closed switch 40-3, conductor 110, closed switch f2 of the erasing relay, winding F, closed switch S3 `and back t0 the negative terminal of the source 16 through closed switch S4. The same action which occurred in the keying of the hundreds digit 4 now results in the keying of the tens digit 4.

Energization of the winding 40 is maintained through closed switch e4, conductor G10, closed switches 40-1 and 40-2 and conductor K10. Switches 40-4 and 40-5 are opened to interrupt respectively portions of conductors and K10 for preventing subsequent energization of control relay windings for digits in the tens set smaller than the digit 4. Energization of winding -F of the erasing relay is maintained through conductor H10 and closed switch f1. At this time the digit 4 is effectively keyed into the tens set. The next step involves the manual opening `of switch S3 to effect deenergization of winding F.

In order to key the units digit 4 of the number 444 into the unit-s set, the key T4 is actuated with the result that winding 4 is energized to close switch 4-1 and to open switch 4-2. Closure of switch 4-1 maintains energization of winding 4 through conductor G1 and closed erasing switches e4 and f4 when key T4 is released. Opening of switch 4-2 effectively interrupts that part of conductor K1 which connects the control relay windings ot digits in the units set which are smaller than the digit 4 whereby a previously keyed lower units digit is erased.

Winding C ofthe third `voltage applicator relay is also energized to close its switches c1 and c2. Closure of c1 maintains energization of winding C when key T4 is released from its actuated position. Closure of switch c2 effectively connects a winding D for energization from the source 16 through closed switches S1, a2, b2 and S4. Energization of winding D is effective to operate a suitable registering device (not shown) which records the keyed number 444 in any suitable manner.

The neXt step involves manual operation of the switch S1' to open this switch. This action interrupts the holding circuit for the windings A, B and C of the voltage applicator relays whereby the switches associated with these windings return to the positions shown in the drawing. The number 444 is, however, still keyed into the keying means 14 inasmuch as the holding circuits for the control relays representing digits of this number are independent of the switch S1. It is further noted at this stage that control relays representing digits in the respective sets which are smaller than the digit 4 cannot be energized by actuation of keys for such control windings. This is 'for the reason that the switches 40044, -40-4 and 4 2 are in their'open positions to .prevent such energization. However, control relays associated with keys representing digits equal to or greater than the digit 4 may be energized through the respective conductors 1100, 110 and K1 in response to actuation of keys for such control relays.

As a result, a number having a value less than 444 cannot be'keyed into the device. If, for example, the number 387 is to be keyed in, the temporary actuation of key 300 causes no effect inasmuch as the circuit including the conductor 1100 is interrupted by the open switch 40044. Consequently, windings A and E remain deenergized with the result that an erasing function by the switch e4 cannot take place. Furthermore, the winding B in the voltage applicator cannot be prepared for energization since the switch a2 remains open. VConsequently, actuation of the keys T80 and T7 in the tens and units sets is ineffective to energize the relays associated with such sets.

Let it be assumed now that the number 444 is to `be keyed in again. S1 is initially closed. Actuation of the keys T400, T40 and T4 eifects energization of windings A, B and C through conductors H100, H and H1 and conductors K100, K10 and K1. However, since conductors 1100 and 110 are interrupted such key actuation is ineffective to cause energization of windings E and F. Consequently, no erasing action takes place but the number 444 will again be registered inasmuch as the winding D will be energized through the closed switches a2, b2 and c2..

Let it be assumed now that the number 445 which is larger than the number 444 is to be-keyed in. For this condition, the device will operate as explained in connection with the number 444 up until the time the units digit 5 is to be keyed. When the key T5 is actuated to key the units digit 5, the winding C of the voltage applicator is energized through closed switches S1, a2, b2, conductor H1, key T5, winding 5, and the closed switches 6-2, 7-2, 8-2 and 9-2 included in conductor K1. Energization of winding C causes closure of switches c1 and c2 with switch c1 maintaining energization of winding C. When winding 5 is energized, switch 5-1 is closed to maintain energization of winding 5 through conductor G1 and closed switches Ve4 and f4. Simultaneously, switch 5-2 is opened to thereby interrupt the holding circuit of winding 4 corresponding to previously keyed units digit 4. When switch c2 is closed, winding D is energized to thereby operate the registering device (not shown) to register the new number 445. After the number 445 is keyed and registered, the switch S1 may be opened to deenergize the windings of the voltage applicator relays.

As a inal example, let it be assumed that the'number 544 is to be keyed. The switch S1 is initially closed. The

key T500 is actuated resulting in initial eifective energization of the winding A followed in order by effective energization of the winding E of the erasing device and the winding 500. Eiective energization of winding E results through conductor H100, key T500 and conductor 1100. This is effective to open switch e4- to thereby erase previously keyed digits 4 and 5 respectively in the tens and units sets by interrupting the holding circuits for the associated control relay windings.

Winding 500 is then eifectively energized and is held inthe energized condition by closed switch 500-1. Closed switch 500-2 transfers windingV 500 from conductor 1100 to conductor K100. Switch 5005 is now open to thereby interrupt the holding circuit for winding 400 corresponding to previously keyed hundreds'digit 4. Switch S2 may now be opened to deenergize winding E to thereby return switch e4 to its illustrated position. The tens and units digits 4 Yof the number `544 may then bekeyed in thesame manner as explained in connection with keying of the number 444.

The keys may be actuated in any suitable manner. VIf desired, the keys may be actuated either manually or automatically in response to the passage of a punched tape relative to the keys which may elect actuation of the keys in any suitable manner according to the numbers represented by the tape punchings.

Although the invention has been described with reference to certain speciiic embodiments thereof, numerous modifications are possible and it is intended to cover all modifications falling within the spirit and scope of the invention.

I claim as my invention:

l. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding to dierent digit places of a number, the keys of each set representing different digits between zero and nine, a source of voltage, a separate control relay for each of said keys, each of said control relays being energizable from said source in response to actuation of its key, control means including first means operable in response to energization of a control relay to maintain energization of such control relay when its key is released to key in the represented digit,

Asaid control means also including second means operable to prevent energization of control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, erasing means energizable from said source in response t0 actuation of a key in a set representing a digit larger than apreviously keyed digit in such set for deenergizing an energized control relay in the next following set, and a registering relay winding energizable in response to eachrkeying of a number for effecting registration of said keyed number.

V2. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding to diiierent digit places of a number, the keys of each set representing different digits between zero and nine, a source of voltage, a start switch, voltage applicator means for applying voltage from said source to said keys, said start switch being etiective when closed to prepare said applicator means for energization from said source, said applicator means being energizable from said source through said closed start switch in response to actuation of a key in the key set corresponding to the highest digit place for permitting the application of voltage to keys in the next following set in response to actuation of a keyin the following set, a separate control relay for each of said keys, each of said control relays being energizable from said source in response to actuation of its key, control means including iirst means operable to maintain enengization of a control relay when its key is released to key in the represented digit, said control means also including second means operable to prevent energization of said applicator means and control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, erasing means energizable from said source in response to actuation of a key in a set representing a digit larger than a previously keyed digit in such set for deenergizing an energized control relay in the next following set, and a registering relay winding energizabe in response to each keying of a number for effecting registration of said keyed number. Y

3. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding Yrespectively to hundreds, tens and units digits, the keys of each set representing diierent digits between zero and nine, a source of voltage, a separate control relay for each of saidkeys, each of said control relays being energizable from said source in response to actuation of its key to operate a plurality of control switches, a tirst control switch of each control relay being effective when operated to maintain energization of its control relay when its actuated key is released to key in the represented digit, a second control switch of each control relay being effective when operated to prevent energization of control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, a tens digit erasing relay energizable from said source in response to actuation of a hundreds key representing a hundreds digit larger than a previously keyed hundreds digit for operating a rst erasing switch, said lirst erasing switch being effective when operated t deenergize the control relay corresponding to a previously keyed tens digit, a units digit erasing relay energizable from said source in response to actuation of a tens key representing a tens digit larger than a previously keyed tens digit for operating a second erasing switch, said second erasing switch being elective when operated to deenergize the control relay corresponding to a previously keyed units digit, and a registering relay winding energizable in response to each keying of a number for eiecting registration of said keyed number.

4. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding respectively to hundreds, tens and units digits, the keys of each set representing different digits between zero and nine, a source of voltage, a start switch, a plurality of voltage applicator relays for applying voltage from said source to said keys, said start switch being effective when closed to prepare a lirst applicator relay for energization from said source, said iirst applicator relay being energizable from said source through said closed start switch in response to actuation of a hundreds key to operate a tirst applicator switch, said first applicator switch being effective when operated to prepare a second applicator relay for energization from said source through said closed start switch, the second applicator relay being energizable through said operated first applicator switch in response to actuation of a tens key to operate a second applicator switch, said second applicator switch being eiective when operated to prepare a third applicator relay for energization from said source through said closed start switch, the third applicator relay being energizable through said operated irst and second applicator switches in response to actuation of a units key to operate a third applicator switch, a separate control relay for each of said keys, each of said control relays being energizable from said source through said closed start switch and the associated applicator relay in response to actuation of its key to operate a plurality of control switches, a first control switch of each control relay being efective when operated to maintain energization of its control relay independent of said start switch when its actuated key is released to key in the represented digit, a second control switch of each control relay being effective when'operated to prevent energization of associated applicator relays and control relays in response to subsequent actuation of keys in each set corresponding to digits smaller than digits previously keyed in each set, a tens digit erasing relay energizable from said source in response to actuation of a hundreds key representing a hundreds digit larger than a previously keyed hundreds digit for operating a rst erasing switch, said iirst erasing switch being effective when operated to deenergize the control relay corresponding to a previously keyed tens digit, a units digit erasing relay energizable from said source in response to actuation of a tens key representing a tens digit larger than a previously keyed tens digit for operating a second erasing switch, said second erasing switch being effective when operated to deenergize the control relay corresponding to a previously keyed units digit, and a registering relay winding energizable in response to operation of said third applicator switch for etfecting registration of the number resulting from successive keying of digits in said hundreds, tens and units sets, said start switch being effective when opened to deenergize said applicator relays for permitting a subsequent keying operation.

5. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding respectively to hundreds, tens and units digits, the keys of each set representing diierent digits between zero and nine, a source of voltage, a separate control relay for each of said keys, each of said control relays being energizable from said source in response to actuation of its key to operate a plurality of control switches, a tirst control switch of each control relay being elective when operated to maintain energization of its control relay when its actuated key is released to key in the represented digit, `a second control switch of each control relay being effective when operated to prevent energization of control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, a tens digit erasing relay energizable from said source in response to actuation of a hundreds key representing a hundreds digit larger than a previously keyed hundreds digit for operating a rst erasing switch, said rst erasing switch being effective when operated to deenergize the control relay corresponding to a previously keyed tens digit, a units digit erasing relay energizable from said source in response to actuation of a tens key representing a tens digit larger than a previously keyed tens digit for operating a second erasing switch, said second erasing switch being eective when operated to deenergize the control relay corresponding to a previously keyed units digit, separate third erasing switches operable in response to energization of each of said crasing relays, said third erasing switches vbeing effective when operated to maintain energization of their erasing relays from said source through paths independent of paths which include keys and control relays, and a separate erasing control switch for each of said erasing relays, said erasing control switches being effective when opened subsequent to the keying of a digit in the associated set to deenergize their erasing relays for permitting the keying of -a digit in the next following set.

6. In -avdevice for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding respectively to hundreds, tens and units digits, the keys of each set representing diterent digits between zero and nine, a source of Voltage, a separate control relay for each of said keys, each of said control relays being energizable from said source in response to actuation of its key, control means including rst means operable in response to energization of a control relay to maintain energization of such control relay when its actuated key is released to key in the represented digit, said control means `also including second means operable to prevent energization of control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, erasing means energizable from said source in response to actuation of a key in a set representing a digit larger than a previously keyed digit in such set for deenergizing an energized control relay in the next following set, erasing control means operable in response to energization of said erasing means to maintain energization of said erasing means from said source through paths independent of paths which includes keys and control relays, and erasing control switch means effective when opened subsequent to the keying of a digit in a set to deenergize the erasing means for permitting the keying of a digit in the next following set.

7. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys 'with the sets corresponding respectively to hundreds, tens and units digits, the keys of each set representing diierentdigits vvbetween zero and nine, a source of voltage, a start switch, voltage applicatonmeans for applying voltage'from said source to said keys, said start switch being effective when closed to prepare said applicator means for energizationfrom said source, said applicator means being energizable from said source through said closed start switch in response to actuation of a key in the hundreds key set for permitting the' application of voltage to keys Yin the tens key set in response to actuation of a key in the tens set, a separate control relay for each of said keys, each of said control relays being energizable `from said source in response to actuation of its key, control means including first means operable to `maintain energization of .a control relay when its actuatedtkey is released Vto key yin the represented digit, said control means also including second means operable toprevent energization of said applicator means and control relays in response to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, erasing means energizable from said source in response to actuation of a key ina set representing a digit larger than a pre viously keyed digit in such setrfor deenergizing an energized control relay in the next following set, erasing control means operable in response to energization of said erasing means to maintain-energization of said erasing means from said source through paths independent of paths which includes keys andrcontrol relays, and erasing control switch means efective when opened subsequent to the keying of a digit in a set to deenergize the erasing means for permitting the keying of a digit in the next following set.

8. In a device for determining the maximum number value of a series of numbers, a plurality of sets of actuable keys with the sets corresponding to different digit places of a number, the keys of each set representing different digits between zero and nine, a source of voltage, a start switch, voltage applicator means for applying voltage from said source to said keys, Said start switch being effective when closed to prepare said applicator means for energization from said source, said applicator means Vbeing energizable from said source through said closed start switch in response to actuation of a key in the key set corresponding to the highest digi-t place for permitting the application of voltage to Lkeys in the next following set in response to .actuation of a key in the `following set, a separate control relay for each of said keys, each of saidV control relays beingenergizable from said` source in responseto actuation of its key, control means including rst lmeans operable to maintain energization of a ycontrol relay when its key is released to key in the representeddigit, said control means also including second means operable to Yprevent energization of said applicator'means and control relays in response to `subsequentactuation of keys in a set corresponding to digits Ismaller than a digit previously keyed in such set, and erasing means energizable from said source in response to actuation of a key in a set representing a digit larger than a previously keyed digit in such set for deenergizing an energized control relay in the next following set. v

9. In a device for determining the maximum number value of a seriesof numbers, a plurality of sets of actuable keys with the sets corresponding respectively to hundreds, tens and units digits, the keys of each set representing different digits between zero and nine, a source of voltage, a separate control relay for cachot said keys, each or" said control relays being energizable from said source in response to actuation of its key to operate a plurality of control switches, a first control switch of each control relay being effective when operated to maintain energization of its control relay when its `actuated key is released to key in the represented digit, a second control switch of each control relay being effective when operated to vprevent energization of control relays inrresponse to subsequent actuation of keys in a set corresponding to digits smaller than a digit previously keyed in such set, a tens digit erasing relay energizable from said source in `response to actuation of a hundreds key representing `a hundreds digit larger than a previously keyed hundreds digitfor operating a iirst erasing switch,.said first erasing switch being effective when operated to deenergize 'the control relay corresponding to a previously keyed tens digit, and a units digit erasing relay energizable from said source in response to actuation `of a tens key representing a tens digit larger than a previously keyed tens digit for operating a second erasing switch, .said second erasing switchbeing effective when operated to ldeenergize the control relay corresponding to a previously keyed units digit.

References Cited in the tile of this patent UNITED STATES PATENTS 

